Problem: William ate 2 slices of pie. Nadia ate 5 slices. If William ate $\dfrac{2}{10}$ of the pie, what fraction of the pie was eaten?
If 2 slices represent $\dfrac{2}{10}$ of the pie, there must have been a total of 10 slices. $\text{fraction of pie eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${7}$ out of $10$ slices. They ate $\dfrac{7}{10}$ of the pie.